I try to keep in touch with all my old friends via e-mail, myspace, IM and etc, but it's hard without being able to see eachother in person. When I go back to visit, it's completely different. We're able to talk and enjoy each others company, do things.. Talking over the phone or over the internet just isn't personable enough.
I still consider them great friends though and try to keep in contact a couple times a year via the phone if nothing else. Nothing beats being in person though. Anything else just isn't enough.